Method for processing images captured with bar code reader having area image sensor
First Claim
1. A method of operating a bar code reader which captures frames of image data, said method comprising:
- (A) defining a region of interest area in an initially captured frame of image data, said initially captured frame of image data including an M×
N array of pixel values, said region of interest including an m×
n, m<
M, n<
N array of pixel values, said region of interest area positioned at a center of said initially captured frame;
(B) searching for a decodable symbol representation within said region of interest;
(C) maintaining an original dimension of said region of interest area if in said searching step (a) a decodable symbol representation is located in said region of interest and (i) said decodable symbol representation located at step (ii) is determined to be positioned entirely within said region of interest; and
(D) automatically expanding a dimension of said region of interest area if at step (B) it is determined that an entire decodable symbol representation is not located within said region of interest area.
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Abstract
In the present invention, a bar code reader captures an initial image map corresponding to a scene, then subjects the initial image map to an interpolation step wherein values for constructed pixels positionally intermediate pixel values of the initial image map are interpolated as a function of the initial image map pixel values bordering the constructed pixels. After an interpolated image map is constructed, the interpolated image map is subjected to a binarization step wherein grey scale pixel values of the interpolated image map are converted into binary (1 or 0) pixel values by way of a thresholding process. In the thresholding process, grey scale pixel values are compared to a threshold in the grey scale range, then set to 1 if they are above the threshold and set to 0 if below the threshold. The pixel values of the resulting binarized interpolated image map are then analyzed to determine the identity of a message which may be encoded in any symbol which may be represented in the binarized interpolated image map.
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Citations
30 Claims
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1. A method of operating a bar code reader which captures frames of image data, said method comprising:
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(A) defining a region of interest area in an initially captured frame of image data, said initially captured frame of image data including an M×
N array of pixel values, said region of interest including an m×
n, m<
M, n<
N array of pixel values, said region of interest area positioned at a center of said initially captured frame;
(B) searching for a decodable symbol representation within said region of interest;
(C) maintaining an original dimension of said region of interest area if in said searching step (a) a decodable symbol representation is located in said region of interest and (i) said decodable symbol representation located at step (ii) is determined to be positioned entirely within said region of interest; and
(D) automatically expanding a dimension of said region of interest area if at step (B) it is determined that an entire decodable symbol representation is not located within said region of interest area. - View Dependent Claims (2, 3, 4)
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5. A method for operating a bar code reader which captures a frame of image data, said method comprising the steps of:
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(A) programming said reader to operate in a low resolution binarization mode and in a high resolution binarization mode, wherein said reader, in said high resolution binarization mode interpolates constructed pixel values corresponding to constructed pixel locations intermediate original pixel locations;
(B) utilizing said low resolution binarization mode when searching said frame of image data to determine if a decodable symbol is represented in said frame; and
(C) driving said bar code reader into a high resolution binarization mode of operation if at step (b) a decodable symbol is located within said frame. - View Dependent Claims (6, 7, 8, 9)
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10. A method for operating a bar code reader having an area image sensor said method including the steps of:
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(A) obtaining a sample or pixel array;
(B) tracking local maxima of a row said array to generate row maximum tracking line data;
(C) tracking local minima of said array to generate a row minimum tracking line data; and
(D) utilizing said row maximum tracking line data and row minimum tracking line data to generate 2D maximum and minimum tracking lines which track, respectively, changes in said row maximum and row minimum tracking line data;
(E) establishing a threshold tracking line between said 2D maximum and minimum tracking lines;
(F) using said threshold tracking line to binarize pixel values in generating a bit map including binarized image data; and
(G) searching for a symbol indicator in said bit map. - View Dependent Claims (11, 12, 13, 14)
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15. A method for operating a bar code reader of the type having an area image sensor, said method comprising the steps of:
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(A) capturing a grey scale image map;
(B) binarizing pixel values of said grey scale image map to develop a binarized bit map while saving said grey scale image map;
(C) searching for a symbol indicator in said binarized image map; and
(D) establishing a region of interest area about a location of located symbol indicator;
(E) utilizing said grey scale image map, interpolating constructed pixel values from pixel values within said region of interest area to develop an interpolated image map; and
(F) binarizing pixel values of said interpolated image map to generate a bit map corresponding to said region of interest area. - View Dependent Claims (16, 17, 18, 19, 20)
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21. A method for operating an area image sensor bar code reader which captures an image map, said method comprising the steps of:
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(A) configuring said reader so that when searching for a symbol indicator in said image map, said reader searches for a symbol indicator within an adjustable region of interest area of said image map which may be adjusted in response to a user input command to adjust at least one of a position, size, or shape of said region of interest area; and
(B) manually inputting a user-input command to said reader to adjust at least one of a position, size or shape of said region of interest area. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A method for operating a bar code reader which captures a grey scale image map, said method including the step of:
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(A) finding a feature of said grey scale image map;
(B) defining a region of interest area about a detected feature detected in step (A);
(C) interpolated constructed pixel values within said region of interest area to develop an interpolated image map; and
(D) binarizing grey scale values of said interpolated image map to generate a bit map comprising binarized pixel values. - View Dependent Claims (28, 29, 30)
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Specification